the reality is much different. until today, all of mcdonald's eggs for its restaurants west of the mississipi came from the huge, closely guarded operation in iowa, run by sparboe farms, the fifth largest in the country. a so-called factory farm where chickens are stacked six to a cage -- barely able to turn around, long defended as a process that turns out billions of cost efficient, safe eggs. so you don't think these are cruel? >> absolutely not. >> reporter: but now, in the wake of an abc news investigation, mcdonald's has fired sparboe farms. citing undercover video made by an animal rights group, mercy for animals, showing mindless, animal cruelty, most of which is too graphic to broadcast. and a highly critical inspection report from the food and drug admiinistration, a companywide warning about unsanitary conditions, including insects, rodents and large numbers of dead birds that could lead to the spread of salmonella.